Also try putting a mouse in a critter carrier in the middle of the room. Place a UTH on the ground and watch it throughout the night. Line the sides of the room with baby powder. If he slithers, you will see it being tracked throughout the room hopefully. Make sure you check in all sofas. If there is a bed nearby, check all the ledges of the frame. Check behind computers or lamps. Check TV's. Anywhere that emits electricity and can warm up.